An alternatively spliced, 5'-truncated MAP1B isoform is expressed in the developing chick nervous system.
Our laboratory has previously characterized a keratan sulfate proteoglycan, named claustrin, and shown by molecular cloning that claustrin and the mouse MAP1B protein share high homology, with claustrin representing a 5'-truncated fragment of MAP1B. In the present study, we examine further the relationship between claustrin and MAP1B, and also describe the isolation of a cDNA encoding the 3'-region of MAP1B, which shares 3'-untranslated sequence, but not coding sequence, with claustrin. We call this partial cDNA 3'-MAP1B-related clone (3'-MRC), since it is homologous to the 3'-region of the mouse MAP1B sequence. We show by Northern analysis that distinct mRNAs are recognized by the claustrin and 3'-MRC cDNAs, and by RT-PCR that mRNAs encoding these distinct MAP1B-related molecules are present in embryonic chick brain and cardiac and smooth muscle. Our data also suggest a higher level of expression of claustrin mRNA in astrocyte cultures, when compared to 3'-MRC. Our data therefore provide new evidence that alternatively spliced variants of MAP1B are expressed in brain, and that at least one of these variants encodes the claustrin proteoglycan.
Burg
M A
MA
Neurobiotechnology Center, Ohio State University, Columbus 43210, USA.
Lee
J A
JA
Cole
G J
GJ
D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D001921:Brain / Q000196:embryology / Q000378:metabolism*; D002642:Chick Embryo; D011508:Chondroitin Sulfate Proteoglycans / Q000235:genetics; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis; D007536:Isomerism; D007632:Keratan Sulfate / Q000235:genetics; D000071234:Lumican; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis / Q000235:genetics*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017384:Sequence Deletion; D017385:Sequence Homology
D011508:Chondroitin Sulfate Proteoglycans; D018076:DNA, Complementary; C000604307:Lum protein, mouse; D000071234:Lumican; D008869:Microtubule-Associated Proteins; C085284:microtubule-associated protein 1B; D007632:Keratan Sulfate